Check whether charset name is available (tortoise#261)

Author: dongweiming

CHANGELOG.rst

@@ -2,6 +2,10 @@
 
 Changelog
 =========
+Unreleased
+------
+- Check whether charset name is available
+
 0.15.4
 ------
 - Don't generate a schema if there is no models (#254)

CONTRIBUTORS.rst

@@ -22,6 +22,7 @@ Contributors
 * Zoltán Szeredi ``@zoliszeredi``
 * Rebecca Klauser ``@svms1``
 * Sina Sohangir ``@sinaso``
+* Weiming Dong ``@dongweiming``
 
 Special Thanks
 ==============

tortoise/backends/mysql/client.py

@@ -4,6 +4,7 @@
 
 import aiomysql
 import pymysql
+from pymysql.charset import charset_by_name
 from pypika import MySQLQuery
 
 from tortoise.backends.base.client import (
@@ -76,6 +77,8 @@ def __init__(
         self._connection = None
 
     async def create_connection(self, with_db: bool) -> None:
+        if charset_by_name(self.charset) is None:  # type: ignore
+            raise DBConnectionError(f"Unknown charset {self.charset}")
         self._template = {
             "host": self.host,
             "port": self.port,